Kapanadze Cousin - DALLY FREE ENERGY

[Jeg]

Clamping TVS or Zener diodes just dissipate this energy without recycling it and they don't adjust their clamping voltage to the Drain voltage like the non-dissipative clamps do.

Hi Verpies
I used a tvs at 100V from drain to source. It is 600W but after some seconds is overheating up to destracture i guess if i let it working like that. Do you think a 1500W one will solve this overheating problem? If i connect it in parallel with my primary, will it operate better in terms of heat?

Yellow green drains. The others are gates. RCD snubber like acula.

[Hoppy]

Hi Verpies
I used a tvs at 100V from drain to source. It is 600W but after some seconds is overheating up to destracture i guess if i let it working like that. Do you think a 1500W one will solve this overheating problem? If i connect it in parallel with my primary, will it operate better in terms of heat?

Yellow green drains. The others are gates. RCD snubber like acula.

Jeg,

I wrote a while back about this. A series resistor needs to be used in series with the TVS if its getting very hot.

[NickZ]

   T-1000:
   I believe that you've brought up a good point, concerning not being able to use the double primary windings to return anything back to the PS. There is also a diode on the output of the PS, not allowing anything back into it from the yoke/grenade device.
The fact that Itsu did made the double windings, does not prove, yet, that there is any benefit at the bulbs, or any lessening of the input consumption on the yoke/grenade devices
   Maybe someone can further explain. Or show how it can make any difference.
  Neither the Ruslan nor Akula devices needed such a change.
   Nor will the normal size primary wire fit on the yoke, if doubled, in any case.
 
    Verpies:  Seams like you are using conventional electronics theory for normal closed circuits, with this open type of circuit.
  If you want to get rid of extra draw, or consumption, the  three fans running to cool this system could be done away with, and just run passive cooling (heatsinks), instead. 
  Or, just use a battery or two, instead of a PS, to return BEMF from the second primary yoke coil, back to a battery?

[verpies]

I used a TVS at 100V from drain to source.

But the scopeshot shows that these TVS diodes are clamping at 240V
It also shows that two times your Drain supply voltage equals to 48V, which means that your Drain supply voltage is 24V.

It is 600W but after some seconds is overheating up to destruction I guess if i let it working like that.  Do you think a 1500W one will solve this overheating problem?

I do not know what kind of current these TVS diodes are bearing, but if it is 3A than 240V*3A=720W pulse power.
So TVS diodes that can withstand 1500W momentary pulse power, would survive.

If i connect it in parallel with my primary, will it operate better in terms of heat?

No, because the winding is a current source so the current will not change and the clamping voltage will not either, so the I*V product will remain the same.


If you were using non-dissipative clamps like Itsu, then your scopeshot would look like the second one attached below, because these clamps clamp at 2*V_CC + V_F, which means around 49V if your V_CC=24V.  If you change your V_CC then these non-dissipative clamps will adjust their clamping voltage accordingly. TVS diodes will not adjust to different clamping voltages.
Smaller Drain-to-Source voltage spike amplitude means, that you can use MOSFETs with lower blocking voltage ratings and lower R_DS-ON.
Also, the power dissipation in the diodes of the non-dissipative clamps will be 0.7V * 3A = 2.1W during the time period when both MOSFETs are OFF, which would mean a fraction of a Watt on average.  That's assuming 0.7V of forward voltage drop (V_F) with these diodes.  If you use Silicon Schottky you can get down to 0.4V.
Last, but not least, the non-dissipative clamps will inject the clamped-off spike energy back into the power supply while the dissipative clamp, like the TVS diode, will dissipate this energy as heat.
The choice is yours.

[magpwr]

Jeg,

I wrote a while back about this. A series resistor needs to be used in series with the TVS if its getting very hot.

hi hoppy,

The flaw is already present in verpies proposed circuit especially if the BEMF is way to high.I already knew about issue but learning is a experience in order to believe isn't it.

TVS diode cannot be used at snubber side it will self destruct from heat and etc.Although higher power zener is more suited for this task of limiting peak voltage.But i don't recomend anyone to use it in this PWM circuit.

TVS diode is more suited for use in preventing too high a spike at the mosfet gates.If base on mosfet\IGBT  datasheet maximum spec gates is mentioned as 18 or 20volts.Then a suitable TVS diode needs to be implemented to protect the gate along with 10k resistor in parallel to GND.

To wrap it up i won't advise anyone to use the recovery circuit.The problem normally arise from resistor to gate 10 Ohms which is considered high.Just stick at 2.2 to 3.3 ohms.

To improve waveform the selection of choke used to connect to center tap of yoke or toroid is important to prevent further ringing even after Akula snubber was implemented.

Gate capacitance of mosfet need to be considered eg 2000pf and below and get a  600volts at least.The old Akula igbts 50n6s2 600volts version.But these are obsolete which generate more heat.

I normally use SIC Mosfet which generate less heat,low switching lost,better Rds on,low gate capacitance <1nf.

Less heat also means smaller heat sink with fan can be used.

I have previously uploaded a simple PWM circuit which works all the way to 350volts dc overkill.

As mentioned previously all TC4XXXX drivers can't do higher than 17volts else you risk destroying your mosfet and mosfet  driver together.

For all the IRXXXx driver are obselete because of the maximum voltage is 20volts which means you should stick with 17...18volts.

IX.... driver can handle up to 30 or 35volts supply max but not required for PWM application.

In the end it's up to individual to select which component to use for efficiency.